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Molecular modelling and investigations of atomistic mechanisms at tribological interfaces

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Title: Molecular modelling and investigations of atomistic mechanisms at tribological interfaces
Authors: Ayestaran Latorre, Carlos
Item Type: Thesis or dissertation
Abstract: Reducing friction and wear inside lubricated contacts could lead to significant improvements in energy efficiency and emissions at a global level. Efforts in this direction are limited by lack of detailed fundamental understanding of the physicochemical mechanisms taking place at tribological interfaces. Molecular modelling can provide valuable insights into the atomic-scale behaviour of these systems in order to drive rational design of new lubricants and engineered surfaces that can meet current and future demands. In this thesis, several industrially-relevant tribological systems are studied by different molecular modelling methods. Firstly, the mechanisms through which different dopants affect the water adsorption and the subsequent hydrophobicity of diamond-like carbon coatings is investigated. The interaction between these coatings and water plays a central role not only on their frictional performance, but also gives clues as to their interactions other polar molecules such as lubricant additives. Secondly, a classical interfacial force field to model the adsorption of organic friction modifier additives on iron oxide is developed and applied to molecular dynamics simulations under boundary lubrication conditions. Finally, the decomposition mechanisms of adsorbed phosphate ester antiwear additives on ferrous surfaces are investigated using reactive molecular dynamics simulations. The effects of surface chemistry and molecular structure are studied, separately for both thermal and mechanochemical decomposition. The work presented here has contributed to a more complete picture of the atomic-scale phenomena at tribological interfaces and has also helped to explain recent experimental results. The techniques developed have paved the way towards rational design of lubricant additives using in silico methods.
Content Version: Open Access
Issue Date: Apr-2022
Date Awarded: Jul-2022
URI: http://hdl.handle.net/10044/1/98894
DOI: https://doi.org/10.25560/98894
Copyright Statement: Creative Commons Attribution NonCommercial NoDerivatives Licence
Supervisor: Dini, Daniele
Ewen, James
Mostofi, Arash
Sponsor/Funder: Afton Chemical (Firm)
Engineering and Physical Sciences Research Council
Funder's Grant Number: EP/L015579/1
Department: Materials
Publisher: Imperial College London
Qualification Level: Doctoral
Qualification Name: Doctor of Philosophy (PhD)
Appears in Collections:Materials PhD theses

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